Lathe or like machine



P. V. VERNON.

LATHE 0R LIKE MACHINE.

APPLICATION FILED NOV. so. 1918.

Patented May 11, 1920.

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- ment of thework can reproduce an accurate PERCY VENALBLES VERN N, 0F COVENTRY, ENGLAND.

I LATHE on LIKE MACHINE.

Specification of Letters Patent.

Application filed November 30,- 1918. Serial No. 264,871.

To all whom it may concern:

Be it known that I, PERCY VENABLES VERNON, a subject of the King of England, residing at Coventry Warwickshire, England, have invented certain new and useful Improvements in Lathes or like Machines, of which the following is a specification.

My invention relates to improvements in grinding machines or lathes for cutting or grinding screws or screw thread gages of the type in which an accurately screwthreaded leader on the headstock spindle engages a fixed nut, and means are employed to rotate the said spindle whereby the screwthreaded leader is caused to travel in the said nut and move the spindle endwise, while the work is held up to and follows the spindle owing to the pressure exerted by the tail-stock center which may be spring pressed from the tail-stock. v The leader is of the same pitch as the thread to be ground or cut, so that a grinding wheel or tool held stationary relatively to the endwise movethread on the work. It is obvious that when using apparatus of this kind, the extent to which the headstock spindle and the tailstock center projectfrom their bearings varies during the travelof the leader in its nut; and consequently the work is not uniformly rigid (relatively to side pressure) during the whole of the said travel. It is the object of my invention to remedy this defect.

According to my invention there is combined with a lathe or grinding machine of the type described a traveling front bearing for the headstock spindle and means (for example a lead screw) operatively connected to the main driving mechanism for imparting motion to the said bearing in the direction of endwise movement of the headstock spindle and at approximately the same speed. In this manner theoverhanging end of the headstock spindle is supported against side pressure notwithstanding the amount which it projects from the headstock spindle bearings during its endwise movement.

Preferably the tailstock spindle is also operatively connected to the main driving mechanism to move in the direction of endwise movement of the headstock spindle and at approximately the same speed. By this construction the tailstock moves endwise with the work which it supports so that the overhang of the tailstock spindle is not sub- Patented. May 11,1920.

stantially affected by the endwise movement aforesaid.

The tailstock and. the front hearing may both be mounted upon a table, longitudinally slidable on the bed of the machine and operatively connected to'the main driving' by the driving worm D mounted on the f drive shaft D The sleeve C carriesthe headstock spindle C which is slidable endwise therein, but is prevented relative rotation thereto by feathers C which engage longitudinal featherways C in the sleeve C.

Mounted in any appropriate manner -to slide longitudinally upon the machine bed A is-a table 'F,-which at the-end nearest the headstock, carries a bearing F to support the overhanging portion C of the head-11 stock spindle C and at the other end caris resiliently thrust outward by a spring G to maintain a continuous end pressure upon;-

' the work held between the centers G C and thereby also upon the headstock spindle C and the leader E. t e

Carried by: a lug'F on the underside of the table F is a nut F which operatively engages the thread of a lead-screw H, whose axis is parallel to that of the headstock spindle C One end of the lead-screw is carried by a bearing B depending from the headstock B and is provided with a spur wheel H which meshes with another spur wheel H fast on the sleeve C. The pitch of the lead screw H in conjunction with the proportions of the spur wheels H H are so chosen that the longitudinal movement of the table F shall be in the same direction, and of the same, or approximately the same amount as the endwise movement of the spindle C under the action of the leader E. It will be seen that by the above described construction Work such as J placed between the centers C and-G -Wi=l-l, if' the travel'of the table F is at the same rate as the end- Wise movement of the headstock' s iindle G 5 preserve its same relative position between the-bearing F and the tailstock Gr and thus be'sapported in a swarm manner against the lateral thrust of the"uttingwoolfcnot shown in the drawing) avhich is carried tiptin" a stationblry part of the maohine' in known manner. I

Whenaleader' iseinployed having a pitch ofthread which causes relight difference between the rate ofendwise mot e'nient er "the headstolik spindle C and that of" the table- F the spring G l-earnestl in-erases the ta i'lstohk spindle G onthe work 17, amid permits its endwis inovein'ent relative to the titilht'hk G While the jheadstoek spindle slides in the E bearing "F "but unless "the threticlto be'cut' on" the'tvork is'of considerable length the meant of overhang of the 'heidstolc'k'"sfiindle G pr the tairsteck spiridle -G *'is"riot seriiisly affected. weensiderttble range of fii'tbh'es have to be cut "\vhihh involve 'largedifierence in theanotiens of the headstock spindle and the "table. ehange wheels may' be provided between the leacl' scr'eiv H and 'its' "driving wheel H When the "leader "on the hea dstock spindle "has a' fineth'iead, itnia'y be advantageous to "make the" pitelr of the lead srir'ew H some- -vvhatf"coarser, anchto drive' it at a corre- -epenaifigl wedacedspeed. I

It will be seen that by the empleymehrof "thelead "screw "H to nib'tfe the tearin F and the tai-lstoc'k G and t wausing their movement to "be in thesaine directionand *ef' the same amount as that of the eridwise 40 niovemeht' of the Iiea'dstOek spindle C the "main leeder'and' its nut are relieved of 'all lead except "that imposed by the cut-ting t'ool' in -"fo'r'in'ingthe thread on the work Even if the aforesaidfmovements are not ignite alikethe only result is ta'cause variai trons of negligiblewalue in the pressure of the spring G '"as-* the =tai'1'st'oelr spindle G moves in the tailstook to compensatefior sunk-difference of 'movements.

*To provide for cutting right and left handed threads 7 the spindle of the leadscrew H may be formed to receive interchangeable leaders H secured thereon in known manner to engage corresponding nuts F carried by the lug F of the table F. Such interchangeable leaders are'of dpiteh proportionalto that'of the main leader E.

Obviously, if desired, the direction of the travel of the tableF' niay beehanged by 'ushr a reversin train of wheels temperate the leackserew H. Y

lVhat I 'elaim' as my invention and desire to"s'efu re by Letters Patent is 1. 111 a lathe or grinding 'in'ac'hine the @ombinatiomwith a "head-steely a tail-stock and a headsteck spindle, of a 1 traveling "from 4 bearin for said "spindle, a screwth eaded leader for 'said spindle;= and a leadoperati'vel Connebted' with the maiin driving me'ohanism the arrangement being s'ueh that a Ti-I'IifOT-In' motion is'- imparted by siaid lead-serew to the said bearin g in the direction of movementof thesaid':spindle and "at 'ractically: the same s'peed; thereby maintaining the same "relative i position ot thework between the sai 6' bearing r and V th 0 "said" ta iii-"stock.

4 "2. "A lathe our-grinding=1na0hine as speci- 3 fied= in claim 1,-W-her'ei1r the tai1st'o'ck'is= also operati'veily' connected *to" the main driving "mechanism to move in the direction oi end- Wise movement-0E the "headstock spindle and at approximatelythe same speed.

3. A lathe on I grinding machine a s specifled in claim Qg'wherein the tai lstock tmd 'the new bearing for the h'eadsto'ck spindle are botlrmounted- *upon a" table, longitudinally slidable on-the bed "of the machine and operated by the lead-shrew engaging a nut on the saidth-ble. V

' In-'-te'stimony'= whereof I have signednny name to this specification in the presence-of I two subscribing Witnesses.

PERCY VENA'BIDES VERNON.

'- Witnesses ROBERTT HAWKINS, 'EVELYN HULL. 

